Among existing communication data transmission technologies, technologies for transmitting Ethernet data over a coaxial cable may be collectively referred to as an EOC (Ethernet Over COAX) technology. In the EOC technology, an end-to-multi-end network topology is adopted and an original coaxial cable in a broadcast and television network is used to implement full-service access of various data. Another Ethernet passive optical network (Ethernet Passive Optical Network, referred to as EPON) technology is an end-to-multi-end optical fiber transmission and access technology, in which downlink data is transferred by adopting a broadcast manner and uplink data is transferred by adopting a time division multiple access manner, so as to flexibly form a tree, star or bus topology, and so on.
Recently, an Ethernet passive optical network protocol over coax (EPON Protocol Over Coax, referred to as EPOC) technology emerges, which combines the EPON technology and the EOC technology and has a two-level topology. FIG. 1 is a schematic diagram of a topology of an EPOC system. As shown in FIG. 1, an EPOC includes: an optical line terminal (Optical Line Terminal, referred to as OLT) 101, an optical network unit (Optical Network Unit, referred to as ONU) 102, a coax media converter (Coax Media Converter, referred to as CMC) 103, and multiple coaxial network units (Coaxial Network Unit, referred to as CNU) 104. The CMC is an entity similar to the ONU and connects multiple CNUs to form a second level topology.
In the prior art, an OLT broadcasts a discovery window (Discovery Window) message to a CMC and an ONU in a network, and after receiving a logical link identifier (Logical Link Identifier, referred to as LLID) registration request sent by a connected CNU, the CMC may forward, in a discovery window, the LLID registration request of the CNU to the OLT. The CMC and the ONU may also send, in the discovery window, their own LLID registration request to the OLT. However, a conflict of LLID registration of the ONU, CMC and CNU might be caused in the discovery window of the OLT.